This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This primary purpose of this study is to evaluate how the recuperative sleep process is affected by a 5-day shift cycle and to use results from this study to formulate more equitable shift cycles to improve the recuperative sleep process, and thereby performance of residents. Residents at Harbor Medical Center with a 5-day shift cycle will be screened using a screening and the Beck?s Depression Index-II questionnaires for eligibility for the study. 40 residents will be recruited and their participation will last between 1 and 3 months. During this time, they will they will be evaluated on two occasions (study phases), each will last a period of 5 days. Their first evaluation (Phase 1) will start during either their 5-day shift cycle or 5-day non-shift clinical posting. The second evaluation (Phase 2) will take place at least 1 month or possibly up to 3 months later. If their first evaluation is done during the 5-day shift cycle posting, then their second evaluation will cross over to the 5-day non-shift posting and vice versa.